2,624 research outputs found

    Effect of preparation conditions on the polymorphism and transport properties of lanthanum molybdates

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    In this work, La6MoO12-based compounds were investigated as part of a new family of materials very competitive as hydrogen separation membranes [1,2]. La5.4MoO11.1 was synthesized by the freeze-drying precursor method and the calcination conditions were optimized in order to obtain single phases. Several cooling rates were applied and different polymorphs were obtained: a simple cubic fluorite symmetry (Fm-3m) for the sample cooled by quenching, and two different rhombohedral (R-3) space groups for the samples cooled at 50 ºC•min-1 and 0.5 ºC•min-1 (see Figure below). For the quenched sample, the Rietveld refinement was satisfactory in a Fm-3m space group. For the other two compositions no structural model was available and were indexed in a R-3 space group, however some small reflections were not given any intensity by the model used. Transmission electron microscopy confirmed the presence of superstructures for those samples. All ceramic materials were obtained with relative densities close to 100% after sintering at 1500 ºC. Stability studies demonstrated that all three polymorphs were stable in oxidizing and reducing conditions at 800 ºC for 48 hours. The three samples present a significant proton contribution to the conductivity at temperatures lower than 800 ºC. These results were confirmed by thermogravimetric analysis. The highest conductivity values were observed for the samples prepared by quenching. The three polymorphs display a small p-type electronic contribution to the overall conductivity in oxidizing conditions and n-type electronic one in very reducing conditions, much more significant for the samples cooled by quenching and at 50 ºC•min-1.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Pigmented corneal ring associated with orthokeratology in caucasians : case reports

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    BACKGROUND: The aim was to report the appearance of a pigmented ring in both eyes of two patients undergoing overnight orthokeratology. METHODS: Two Caucasian patients, one male and one female, were fitted with orthokeratology lenses to correct myopia between -2.00 and -2.50 DS with Paragon corneal refractive therapy lenses worn overnight. Treatment was successful in both patients achieving uncorrected vision of 6/6 or better monocularly under high (100 per cent) and low (10 per cent) contrast conditions. RESULTS: At the six-month visit both patients presented with pigmented rings under slitlamp examination in both eyes. The location of the ring was consistent with the corneal area being flattened for myopic correction. Clinical examination was otherwise normal. CONCLUSIONS: Despite being initially reported in Asian patients from Hong Kong, a pigmented ring related to orthokeratology treatment is also present in Caucasian patients, reducing the potential role of an ethnic link. Further large-scale studies need to be done to estimate the actual incidence of this condition and the potential implications for corneal health

    Good practice in mental health care for socially marginalised groups in Europe: a qualitative study of expert views in 14 countries

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    This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

    Expansion of the agricultural frontier in the largest South American Dry Forest: Identifying priority conservation areas for snakes before everything is lost

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    Conservation planning relies on integrating existing knowledge, social-environmental contexts, and potential threats to identify gaps and opportunities for action. Here we present a case study on how priority areas for conservation can be determined using existing information on biodiversity occurrence and threats. Specifically, our goals are: (1) to model the ecological niche of twelve endemic snake species in the Dry Chaco Forest, (2) to quantify the impact of the deforestation rates on their distributions, (3) to propose high priority areas for conservation in order to improve the actual protected area system, and (4) to evaluate the influence of the human footprint on the optimization of selected priority areas. Our results demonstrate that Argentinian Dry Chaco represent, on average, ~74% of the distribution of endemic snake species and deforestation has reduced suitable areas of all snake species in the region. Further, the current protected areas are likely insufficient to conserve these species as only very low percentages (3.27%) of snakes’ ranges occur within existing protected areas. Our models identified high priority areas in the north of the Chaco forest where continuous, well-conserved forest still exists. These high priority areas include transition zones within the foothill forest and areas that could connect patches of forest between the western and eastern Chaco forest. Our findings identify spatial priorities that minimize conflicts with human activities, a key issue for this biodiversity hotspot area. We argue that consultation with stakeholders and decision-makers are urgently needed in order to take concrete actions to protect the habitat, or we risk losing the best conservation opportunities to protect endemic snakes that inhabit the Argentinian Dry Chaco.Fil: Andrade Díaz, Soledad María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del Noroeste Argentino. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto de Bio y Geociencias del Noroeste Argentino; ArgentinaFil: Sarquis, Juan Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Loiselle, Bette A.. University of Florida; Estados UnidosFil: Giraudo, Alejandro Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina. University of Florida; Estados Unidos. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias; ArgentinaFil: Diaz Gomez, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del Noroeste Argentino. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto de Bio y Geociencias del Noroeste Argentino; Argentin

    Machine Learning Improves Risk Stratification in Myelodysplastic Neoplasms: An Analysis of the Spanish Group of Myelodysplastic Syndromes

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    Machine learning; Risk stratification; Myelodysplastic neoplasmsAprendizaje automático; Estratificación del riesgo; Neoplasias mielodisplásicasAprenentatge automàtic; Estratificació del risc; Neoplàsies mielodisplàstiquesMyelodysplastic neoplasms (MDS) are a heterogeneous group of hematological stem cell disorders characterized by dysplasia, cytopenias, and increased risk of acute leukemia. As prognosis differs widely between patients, and treatment options vary from observation to allogeneic stem cell transplantation, accurate and precise disease risk prognostication is critical for decision making. With this aim, we retrieved registry data from MDS patients from 90 Spanish institutions. A total of 7202 patients were included, which were divided into a training (80%) and a test (20%) set. A machine learning technique (random survival forests) was used to model overall survival (OS) and leukemia-free survival (LFS). The optimal model was based on 8 variables (age, gender, hemoglobin, leukocyte count, platelet count, neutrophil percentage, bone marrow blast, and cytogenetic risk group). This model achieved high accuracy in predicting OS (c-indexes; 0.759 and 0.776) and LFS (c-indexes; 0.812 and 0.845). Importantly, the model was superior to the revised International Prognostic Scoring System (IPSS-R) and the age-adjusted IPSS-R. This difference persisted in different age ranges and in all evaluated disease subgroups. Finally, we validated our results in an external cohort, confirming the superiority of the Artificial Intelligence Prognostic Scoring System for MDS (AIPSS-MDS) over the IPSS-R, and achieving a similar performance as the molecular IPSS. In conclusion, the AIPSS-MDS score is a new prognostic model based exclusively on traditional clinical, hematological, and cytogenetic variables. AIPSS-MDS has a high prognostic accuracy in predicting survival in MDS patients, outperforming other well-established risk-scoring systems

    Microsurgical Techniques in Cerebral Revascularization

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    The surgical management of patients with cerebrovascular disease is reviewed. Our approach to the management of extracranial cerebral vasculature is discussed first, and increasingly more complex areas are then presented. Our discussion reviews the applications of carotid endarterectomy, extracranial-intracranial bypass procedures, and vertebral extracranial reconstruction
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